


Blood in the Waves

by quixartically



Category: Sherlock (TV)
Genre: Anal Fingering, Anal Sex, Character Death, Character Transformation, Death Threats, Domestic Violence, Eggpreg, Eventual Relationships, Eventual Romance, Forced Egg impregnations, Forced Ejaculation, Forced Masturbation, Forced Orgasm, Injury, Interspecies Sex, Knotting, Loss of Virginity, M/M, Miscarriage, Mpreg, Mutual Pining, Near Death, Near Death Experiences, Non-Consensual Oral Sex, Oral Knotting, Pining, Rape/Non-con Elements, Rough Oral Sex, Threats of Violence, Top!Mycroft, Unwanted Knotting, merman au, ovisporator, top!Sherlock
Language: English
Status: In-Progress
Published: 2020-02-06
Updated: 2020-02-06
Packaged: 2021-02-27 23:01:36
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con
Chapters: 2
Words: 2,646
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22583722
Author URL: https://archiveofourown.org/users/quixartically/pseuds/quixartically
Summary: Sherlock kept his eyes on the boat. Nearly every man, woman and child on it were Alphas. Mating season was quickly approaching and the Siren had yet to find a suitable Omega to produce for him. Irene buggered at him for being so picky, but honestly, she chose horribly every mating season. She was fond of tiny Omega women that she could destroy while pumping clutches into them. But what she failed to see was that by the time her offspring had hatched, there'd be little for her clutch to feed on. No. It was Sherlock's first mating season and he was sure to do it right. Which was why, of course, with less than a week of hunting season left, Sherlock was struggling to find a suitable partner to lay his clutch into.He pumped his strong fins,and swam closer to the large cargo ship. He was beginning to fall impatient. He lifted his face from the water and began  to sing, willing any Omegas who believed themselves to be in a fit and healthy shape to jump over board.  Two figures appeared at the edge and began to climb the railing. Sherlock swam quickly and took the first to fall, a young blonde man, into his claws. Sherlock grinned at his fortune.Now the fun would begin.
Relationships: Jim Moriarty/John Watson, Mycroft Holmes/Greg Lestrade, Sherlock Holmes/Jim Moriarty, Sherlock Holmes/John Watson
Comments: 14
Kudos: 107





	1. The Mate

**Author's Note:**

> WARNING: RAPE/ NONCONSENUAL SEXUAL RELATIONS WILL OCCUR IN THIS FAN FICTION. FOR A WHILE. Also, Domestic Violence and Graphic depictions of violence. THIS IS NOT YOUR AVERAGE LITTLE MERMAID STORY. THIS IS GOING TO BE SICK, AND FILTHY AND VERY VERY VERY BLOODY! You've been warned.

Sherlock kept his eyes on the boat. Nearly every man, woman and child on it were Alphas. Mating season was quickly approaching and the Siren had yet to find a suitable Omega to produce for him. Irene buggered at him for being so picky, but honestly, she chose horribly every mating season. She was fond of tiny Omega women that she could destroy while pumping clutches into them. But what she failed to see was that by the time her offspring had hatched, there'd be little for her clutch to feed on. No. It was Sherlock's first mating season and he was sure to do it right.  
No skinny looking Omega would satisfy him.  
Which was why, of course, with less than a week of hunting season left, Sherlock was struggling to find a suitable partner to lay his clutch into. Sherlock growled into the water, bubbles escaping his gills angrily and ignored Mycroft's look of indignation. His elder brother had insisted on coming along, as he had been too rough with his mating partner and had broken the fragile thing already. He pumped his strong fins, which were the color of an oil slick and swam closer to the large cargo ship.  
He was beginning to fall impatient. He lifted his face from the water and began to sing, willing any Omegas who believed themselves to be in a fit and healthy shape to jump over board. Mycroft laughed, despite the angry flicker Sherlock's fins where displaying.  
Wrong move on his part. Sherlock halted his song and turned on him, claws slashing at his kin's chest drawing four angry red lines. He was about to sink his teeth in as well when Mycroft held his webbed hands in front of him in a surrender.  
"For Neptune's sake, Sherlock!" He spoke to him in his head. "Apologies! No ill will meant! Honestly!"  
Sherlock smirked, finding it amusing that his brother, who was a full seven seasons older than he was, was frightened of him. He supposed that it was natural of course. He was the strongest and most deadly of their entire pod. Sherlock returned to the surface and continued his song.  
In nearly no time at all, two figures approached the edge of the boat and even from here Sherlock could see their blank faces, eyes glazed over as his lullaby took over their minds, their hearts, their very souls. Sherlock could hear voices, no doubt loved ones begging for them to stop fooling about.  
The two began to climb the railings and a shrill scream of, “Gregory, no!” echoed across the air, followed by, “John Hamish Watson, what on Earth is the meaning of this, you come down right now before I get your wife! She’ll put you straight!!”  
Mycroft laughed again. The smarmy sadist loved this part. He began to swim closer as the two fell. Sherlock swam quickly after him and took the first to fall, a handsome blonde young man, into his claws.  
He had fallen unconscious the second he hit the water, and Sherlock sank his sharp fangs into his neck, the glands under his tongue pumping a paralyzing venom into his veins. The venom would keep him oxygenated while the Siren used him. It would also likely keep him inebriated enough that he wouldn’t fight back. Hell, he might even like it.  
Mycroft quickly followed suit, grabbing the other man, who had not gone unconscious and was now fighting against the much stronger sea monster. Sherlock watched with interest as Mycroft wrapped his long midnight purple tail around the man and squeezed, the sound of breaking ribs filling the ocean. The man screamed a rasped scream as his breath supply was quickly stolen from him. Finally, he hung limp in his captor’s grasp, his pale face tinted with blue and Mycroft quickly sank his teeth into his neck. Almost immediately, colour returned to his cheeks.  
Mycroft unwound himself and swim towards his brother. As Sherlock got a better look at his brother’s mate-to-be, he found himself growing jealous. Though Mycroft’s catch had the beginnings of the salt and peppered hair that often suggested that a human was aged, he had thick wired muscles and was a much larger form than Sherlock’s catch.  
“I want that one. Give him here.” Sherlock demanded. “Mine is far too small, the poor thing would be torn from my size.” In reality, Sherlock’s catch was nearly just as muscular, but Sherlock had already found a large scar on his shoulder and was clearly much shorter. Sherlock certainly didn’t want short children.  
Mycroft scoffed. “You should’ve gone for him then. He’s mine, and besides, he needed to be injured in order to render him unconscious. I’ll have to wait at least a week to begin, and you wouldn’t want that, now would you?” Mycroft began to shred the clothing of his man away, exposing the heavy bruising that was already forming across his chest.  
Sherlock hated to admit it, but he was right. Now that he had his mate, his cock was already rousing inside him, his first season making his senses much stronger than a Siren who had been through the process once or twice already. He began to unclothe his man as well.  
“Oh, look, mine has a rather large prick, don’t you think?” Mycroft asked, pointing. “This season may be fun after all…” Sherlock didn’t spare him a glance and instead curled his lip in disgust,  
It was well known that Mycroft liked to play pretend with his prey, making it seem as if a connection had been formed. He had spoken many a time of how male mates would often be distrusting and would want to penetrate him before even thinking about letting the Siren enter him. The thought made Sherlock’s stomach turn in a peculiar way. His brain told him that it was unnatural, yet his hormones told him not to be so hasty.  
“That’s all very well, but he is complete muscle! Not an ounce of fat at all, he’ll be all tough to your clutch once they arrive. You may have to chew him first.” He patted the soft layer of fat on his own mate in satisfaction. “Whereas mine will be well fed, don’t you agree?”  
Mycroft rolled his eyes and glanced over in disgust. “Oh, shut it. You’d best get to your cave, you’ve already an erection.” Sherlock looked down. Mycroft was right, damn him. His cock was already peeking from the slit that rested in-between his pelvic fins. Sherlock huffed and turned away, cradling his mate in his arms before swimming away to the underwater cave he’d already prepared.  
This particular cave was large and had spiraling vents leading to nowhere. If his prey tried to escape, he’d be hopeless. He’d starve before he found the way out. Thinking of food, Sherlock kept an eye out for any fish along the way. He knew that he would need to keep his human alive during the season, and after succumbing to a Siren’s Song, the man’d be exhausted and no doubt hungry. He spotted a school of yellowtail tunas and easily snatched one up, the dying animal trailing blood into the water behind them, leaving a gory spectre of what the poor man had in store for him.  
Now the fun would begin.


	2. Awakening

**Summary for the Chapter:**

> John wakes up to strange creature attempting to cramp raw fish down his throat. They speak for a moment before the veteran realises that Sherlock is not meant to be his friend.

**Notes for the Chapter:**

> Non con will be in this chapter. It will be detailed and graphic and probably bloody. I will have it sectioned off and will end the chapter with a short and vague description of what happened. The scene will begin after the words: John react quickly and took a deep breath before he was dragged into the water. And end at the words: He glared at Sherlock's blissed out face with an envious anger. 

John's head was pounding. His skin was clammy and sticky with salt and sweat. He made to sit up and nearly gagged. A piece of bloody fat and sinew was being pushed into his mouth. John choked and brought his head away. 

"Quit that, eat or you'll starve." The man in front of him said. John blinked, trying to get the sand from his eyes and see the man clearly. 

"Sorry, who are you?" He asked, his throat aching, burning with thirst. The man put his hand back into his face. 

"Eat it."he said again. John had no choice this time, but he nearly threw up as it went down. It was clearly some sort of fish, but it wasn't cooked. He turned his eyes on the man and was about to give him a severe scolding when he saw just who he was. 

The man was fair with seafoam grey eyes and a mess of curly black hair that tumbled over his shoulders. He was well built, thin but muscular, his flat stomach leading down to a long, dark fish's tail.

John had heard the legend of merpeople before, yet had never believed in them. Though he supposed there could be no denying it now. "Er... sorry, who are you?" He asked carefully. 

"My name is Sherlock. That's all you need to know." The man- fish man? -merman?- said as he dug his sharp nails into a large fish and tore another chunk out and handed it to him.

"Thanks...Sherlock..." he set it down on a rock beside him and looked around. He appeared to be in a cave but could not see an opening to it. Everything was quiet for a moment before Sherlock moved his tail onto the rock and began to scoot closer to him. He looked clumsy on land, though he was definitely more coordinated on land than John would have thought. 

Sherlock took John's face in his hands and the blonde man immediately pulled away. The merman smirked and ran a clawed finger down his chest. John suddenly realised that he was naked.

"Uhm!" He coughed. "I beg your pardon, but if you could bring me back to the boat where you found me please... and give me my clothing. Mary must be horribly worried." He stood up hastily and looked around, trying to find a way out, adrenaline pumping through him. The only exit he could see was a long corridor and the deep pool of water that Sherlock had been lying in. 

Before he could dart towards the corridor, Sherlock's large hands were wrapped around his ankles, nails digging into his skin and drawing blood. Sherlock yanked John's feet out from under him. The fragile human yelped as his head smacked the wet rock and he felt blood bloom across the back of his head. 

Sherlock was upon him, crouching over his body and John gasped as he licked from his navel all the way up to a very sore part in his neck. John used all the strength in his body to push Sherlock off of him.

"Beg your _pardon!_ " he cried out as Sherlock was forced back into the tide pool. "For Christ's _sake_ , you don't just _lick_ a man you've barely met, _especially_ not a married man! Are you mad?"

Sherlock gave him a sinister look. "Forget your wife." He said, pushing himself up on the rock again. "And watch- your -to _ngue-_ when you speak to me." He latched onto John's ankle and pulled him across the rock, scraping the skin on his back horribly. "You have no wife now. You're _mine."_

Sherlock grinned and John could see a mouth full of razor-sharp teeth. Before he could even scream, Sherlock had sunk them into his neck. Instantly, John felt as if he was on a cloud. He couldn't move. "P-please." He begged. "Please, just let me go." Sherlock released John's neck, his blood dripping from his teeth and mixing with his venom. He gave off an eerie laugh. "No." He said before promptly pulling John into the water and wrapping his fourteen-foot tail around him, holding him still. John react quickly and took a deep breath before he was dragged into the water.

John felt Sherlock's claws begin to dig into the skin of his arse, pulling the cleft open. 

_"Please God, don't let this truly be happening."_ John thought as he felt the blunt wet tip of something _very_ large begin to push into him. John squeezed his eyes shut as he heard Sherlock gasps in front of him. They had sunk nearly to the bottom of the seafloor and John was quickly running out of air. 

He began to beat his fists against the Siren's chest angrily. _"I'll drown you brute!"_ He thought anxiously, his eyesight beginning to grow dark. He felt Sherlock position his roughly scaled lips over his own and nearly vomited. 

_"Breathe, you idiot. My gills will filter the oxygen for you."_

The voice sounded through his head and he inhaled greedily, watching Sherlock's gill flaps flutter and they gave him the life-breath he needed. At least John knew that he was wanted alive...

Sherlock moved suddenly, sheathing his entire cock, nearly fifteen inches long into John's unprepared arse. John screamed into the water and immediately went back to Sherlock for air. 

Sherlock pounded into him relentlessly, gripping John's hips and dipped his claws deep into the muscle there. John was certain that if he wasn't underwater, tears would be leaking from his eyes nonstop. 

He'd slept with men before, but this was so much different. Sherlock's prick slammed into him with the force of a hammer into a nail, so hard that John thought that he may have actually broken his pelvis.

John's prostate was being smashed into oblivion, with each thrust the pain doubling, tripling, quadrupling, as the small gland was bruised over and over. 

Suddenly, John felt a clawed hand on his flaccid cock. It began to pump it roughly, nearly painfully. John thought bitterly that it was nice of the fish to think of his arousal while he raped him into oblivion. 

John felt his orgasm build inside him, despite everything, and nearly cried out as his come was spent into the water. 

Sherlock's grip on him became so horribly tight that he wasn't able to draw in a breath, even will Sherlock's gills doing all the work for him. His thrusts stopped and John felt a knot swelling in his arse. He squirmed and tried to get free, but to no avail. He could feel ropes of hot liquid filling him, followed by an uncertain amount of round objects into him as Sherlock let out a loud moan into the water, his lips breaking free from John's. John scratched his fingernails against Sherlock's face, desperate for air. Instead of obliging, Sherlock unwrapped his tail from around John and with much difficulty- they _were_ still connected after all- vaulted them to the surface. John gasped as soon as his head broke to water and breathed heavily. Tears were indeed falling from his eyes. He glared at Sherlock's blissed-out face with anger. 

"How _dare_ you?!" John screamed, breaking Sherlock from his reverie. "How dare you do this to me? How dare you take me like that, nearly drown me, who in the hell do you think you are?!"

Sherlock glowered. His venom wasn't working as well as it should be. He grabbed John's wrist and squeezed angrily. "Haven't I told you to mind your mouth when speaking to me?" He growled lowly, his deep baritone voice reverberating through the cave. 

John let out a yell of pain as he felt the bones in his hand squeeze together and begin to crack. 

"You. Will. _Never_ speak to me that way." He growled. "You are only needed until you give birth. And then you will be eaten by my clutch. I can choose whether or not to snap your neck before they tear into your flesh, remember that." He squeezed harder to emphasize and John screamed as he felt his wrist shatter.

"Do you understand me?" Sherlock asked smugly as his knot deflated and pulled away.

John nodded desperately and Sherlock was satisfied. "You can deal with the pain of that for a few more hours. If you're good, I'll heal you." 

John nodded and sobbed quietly. "Yes sir. Sorry, sir."

Sherlock laughed and handed him another chunk of yellowtail.

"Eat." He demanded.

John didn't wait for his other wrist to be broken.

**Notes for the Chapter:**

> Basically, Sherlock raped John very violently. John was unable to breathe and thought that Sherlock was in some way good because he let him breathe through his mouth with the use of his gills. John felt his innards begin to bruise heavily. Sherlock forced orgasm from him and then knotted him to forcefully that it was difficult for John to breathe even with the help of Sherlock's gills. Sherlock returns them to the surface.

**Author's Note:**

> This fic is gonna be raunchy. Basically, I've been obsessed with mermaid AU's lately and it has completely frustrated me that no one has written anything that is in accordance to the original Siren legend. So I'll explain a bit. The original Siren's would lure people off their boats to have nonsensual and usually painful sex with them in order to procreate. The reason of this is because Siren's are hybrids and therefore cannot produce offspring together. Once the offspring are born (or in this case hatched) the mate then becomes the first meal for the Siren young. Honestly, I'm not sure if Sherlock and John's kids are gonna eat John yet, but lets just consider it a possibility. So yeah. If you're squeamish, this probably isn't the fic for you.


End file.
